Heating and cooling systems for buildings typically include a heating unit which produces heated air and a cooling unit which produces cool air. The hot or cool air is then delivered into rooms of a building through ducts and vents which open into the rooms. In addition, it is common to include air return vents and ducts which return air from one or more rooms of a building back to the heating unit or cooling unit. Thus, air is circulated from the heating and cooling unit, into the rooms, and then back to the heating and cooling unit.
The placement of the vents which deliver heated or cooled air into a room, and the placement of return vents which pull air back out of a room can vary depending on the building design. It is common to place such vents in the walls of a room, in the floor of a room, or in the ceiling of a room.